If you're making a paid Android app you'll probably have problems with a specific issue of LGPL: substitutability. Generally, it states that when you distribute a combined work you have to provide a user with possibility to substitute the library with a different version (e.g. newer). Very doubtful in the case of DEX file, as mentioned in previous comments.
An alternative to a single DEX file is to make from a dependent library a separate application, released on LGPL. In such an application you create a service to which you connect from your paid application. Then, to substitute the LGPL library with newer version only recompilation and reinstalling the library's APK is required.
The hassle is, of course, that now you have more than one APK to install.
