At Dear Author, Jane Litte goes into the ever contentious subject of e-book pricing and points out that limited time free or 99 cent promotional prices can backfire or are at least not nearly as effective as they once were.
Another unintended effect of sales and free promotions is that they train readers to wait for the book to go on sale or free before downloading it. Because, as Jane Litte points out, “almost every self published author has their book on sale at 99c at some point”.
Jane Litte also points out that loyal fans of an author who buy a book for the full price on or pretty close to release day often feel cheated when the same book is put on sale a few days or weeks later. I can totally understand this sentiment.
Now price-pulsing and giving away books for free, either via KDP Select free days or via a mechanism known as permafree along with advertising those sales and giveaways via sites like Bookbub, are indie author marketing techniques that are not just largely unquestioned in the self-publishing community, but also considered obligatory for many.
Nonetheless, I have never used any of those techniques. I hardly ever change my prices, except for minor adjustments whenever Amazon opens a new Kindle store somewhere, and over the course of my indie career I have given away maybe 220 books for free, mostly via coupons, giveaways and bundles.
Why do I eschew such common indie marketing techniques as price pulsing and free giveaways? The reason is the German fixed book price agreement, which among other things forbids reduced sale prices as well as any price changes within the first 18 months after publication for books published in Germany.
Now nobody is quite sure whether the fixed book price agreement applies to self-publishers or not. Even the association of German booksellers and publishers gives contradictory information. The main issue seems to be whether self-publishers count as publishers or not.
However, until the issue has been decided one way or another (which probably won’t happen until someone goes to court over the issue), German indies run the risk of paying pricey penalty fees for violating the fixed book price agreement.
Therefore, Pegasus Pulp adheres to the German fixed book price agreement. This means that you don’t have to worry whether one of our e-books will be discounted two weeks after publication, because it won’t happen. More information about our e-book pricing scheme can be found in the FAQ.

You do realize that the book price agreement only regulates books published in German, don’t you? http://www.gesetze-im-internet.de/buchprg/__2.html
I have both German and English books.